Revieir of Recent Geologicdl lAteralnre. 61 "^ 
species from North America, which he calls a new cephalopod type be- cP -i 
cause of the structure of the apical end, and he called the same by a '^ ■" 50 
new name, Nanno auleina Clarke. Sardeson* (18.9J:) and Batherj (1894) 
both pointed out that Nanno is far from a new cephalopod type. Hyatt J 
(1895) confirmed in main Clarke's description of the apical end of Nanno ^ 
auleina. Holm here quotes in a foot-note Hyatt's introductory words, o 
viz., "The discovery and description of this genus by Prof. J. M. </> 
Clarke has materially added to our knowledge of the structure and de- 
velopment of the siphon in the Endoceratidce and thrown a new light 
upon the affinities of the forms of this group," and comments upon 
them as inexplicable, inasmuch as Sardeson and Bather had pointed 
out that Holm had in 1886. or nine years earlier, more thoroughly and 
extensively descriVjed the cephalopod type in question. 
Further Hyatt considered Nanno auleina, because of the structure of 
the siphonal tubes, as generically distinct from Endoc.cras belenmiti- 
fornie Holm, but he seems, says Holm, not to have had sufficient mate- 
rials. He is quoted much in full because his observations are so indefi- 
nite. 
Holm§ (1895) described and figured the endosiphonal structure of 
Endoceraa (Nanno) belemnitifornie and shows the same to be like that 
of E. loahlingbprcjl Foord, with a cicatrix opening in the same manner 
as in Piloceras, from which it was concluded, — Bather's views notwith- 
standing, — that E. helenmitifovnie and related forms, similar to other 
Naatiloidea, have a fragile, easily destructible protoconch. The near 
relationship between Nanno anlema Clai-ke and Endoceras belemniti- 
fornie Holm was determined and Nanno adopted as a subgenus of En- 
doceras. 
After reviewing the literature Holm presents further ob.servations 
upon the apical structures of Endocevaa. He recognizes two tyjjes of 
these structures in Endoceras, but considers the division of the genus 
as impracticable, since the apical cones of very few species of this large 
group are known, and among the few is not found the type species it- 
self of Endoco-as. He therefore recognizes two subgenera. Nanno, type 
E. anlema, (Clarke) and Suecoceras, type E. barrandei Dew., the former 
of which he considers as the more primitive form. He defines them as 
follows: 
SuBGEN. 1. Nanno (Clarke). Siphon with the apical end strongly 
swelled so that back of the first loculus thei*e is formed an apical cone 
of the shell, which is entirely filled by the sijjhonal apical cone, the 
latter equalling in length, in all known cases, the combined width of at 
least three of the first chambers. Thereafter the siphon tapers for- 
wards so rapidly that the same attains its normal dimension within the 
third septal chamber. 
SuBGEN. 2. SuEcocERAS Holui. Siphou completely filling the shell's 
apical end, with narrow apex, and on the siphonal side in contact with 
*Ame;r. Geol., vol. 14, Dec, 1894, p. 402. 
tNatnral Science, vol. .5, No. 34, Dec, 'UJ, p. 431. 
IAmer. Geol., vol. 16, July, l^y."), p. I, pi. 1. 
.tjGeol. Foron. FOrh., vol. 17, p. (510, pi. 22, fif?. 9-13. 
